Hamburg police were forced to request further support from all German federal states because of the extent of the disorder, with many coming from Berlin and Mecklenburg-Vorpommern.

A senior police officer told WELT: “We can only hope that the rumours disappear that international left-wing extremists want to attack the capital [Berlin] in parallel. Because these indications have existed for quite some time.”

So far, some 20,000 policemen from all over Germany have been deployed in the city to safeguard the meeting of world leaders.

Police estimate that 8,000 violent individuals are currently in the city, with 12,000 attending Thursday night’s protest. The biggest demonstration, with up to 100,000 participants, is expected on Saturday.

Thursday night’s violence erupted less than an hour after Chancellor Angela Merkel met with President Donald Trump and the event descended into chaos at around midnight.